<template>
  <view>
    <!-- 使用自定义的搜索组件 -->
    <my-search @click="gotoSearch"></my-search>
    <view class="scroll-view-container">
      <!-- 左侧的滚动视图区域 -->
      <scroll-view class="left-scroll-view" scroll-y="true" :style="{height: wh + 'px'}" >
       <block v-for="(item,i) in cateList" :key="i">
         <view :class="['left-scroll-view-item', i === active ? 'active' : '']" @click="activeChanged(i)">{{item.cat_name}} </view>
       </block>
         
      </scroll-view>
      
      <!-- 右侧的滚动视图区域 -->
      <scroll-view class="right-scroll-view" scroll-y="true" :style="{height: wh + 'px'}" :scroll-top="scrollTop">
        <view class="cate-lv2" v-for="(item2,i2) in cateLevel2" :key="i2">
          <view class="cate-lv2-title">/ {{item2.cat_name}} /</view>
          <!-- 动态渲染三级分类的列表数据 -->
          <view class="cate-lv3-list">
            <!-- 三级分类 item 项 -->
            <view class="cate-lv3-item" v-for="(item3,i3) in item2.children" :key="i3" @click="gotoGoodsList(item3)">
              <!-- 图片 -->
              <image :src="item3.cat_icon"></image>
              <!-- 文本 -->
              <text>{{item3.cat_name}}</text>
            </view>
            
          </view>
        </view>
        
      </scroll-view>
      
    </view>
  </view>
</template>

<script>
  import badgeMix from '@/mixins/tabbar-badge.js'
  export default {
      mixins: [badgeMix],
    data() {
      return {
        // 当前设备的可用高度
        wh: 0,
        //分类数据列表
        cateList:[],
        //当前选中项的索引，默认第一项被选中
        active:0,
        //二级分类列表
        cateLevel2: [],
        //滚动条距离顶部的距离
        scrollTop: 0
      };
    },
    onLoad() {
      const sysInfo = uni.getSystemInfoSync()
      this.wh = sysInfo.windowsHeight - 50
      this.getCateList()
    },
    methods: {
     async getCateList() {
        //发起请求
      const { data: res} = await uni.$http.get('https://api-hmugo-web.itheima.net/api/public/v1/categories')
      //判断是否获取成功
      if(res.meta.status !== 200) return uni.$showMsg()
      //转存数据
      this.cateList = res.message
      //为二级分类赋值
      this.cateLevel2 = res.message[0].children
      },
      activeChanged(i) {
        this.active = i
        //为二级分类列表重新赋值
        this.cateLevel2 = this.cateList[i].children
        
        this.scrollTop = this.scrollTop === 0 ? 1 : 0
      },
      // 点击三级分类项跳转到商品列表页面
      gotoGoodsList(item3) {
        uni.navigateTo({
          url: '/subpkg/goods_list/goods_list?cid=' + item3.cat_id
        })
      },
      gotoSearch() {
        uni.navigateTo({
            url:'/subpkg/search/search'
        })
      }
    }
  }
</script>

<style lang="scss">
 .scroll-view-container {
   display: flex;
   // 让父容器独立占据视口高度，避免滚动穿透
   height: 100vh; 
 }
 .left-scroll-view {
   width: 120px;
 }
 .left-scroll-view-item {
       line-height: 60px;
       background-color: #f7f7f7;
       text-align: center;
       font-size: 12px;
       
       &.active {
         background-color: #ffffff;
         position: relative;
         
    // 渲染激活项左侧的红色指示边线
        &::before {
            content: ' ';
            display: block;
            width: 3px;
            height: 30px;
            background-color: #c00000;
            position: absolute;
            left: 0;
            top: 50%;
            transform: translateY(-50%);
        }
      }
 }
 .cate-lv2-title {
   text-align: center;
   font-size: 12px;
   font-weight: bold;
   padding: 15px 0;
 }
 .cate-lv3-list {
   display: flex;
   flex-wrap: wrap;  //在一行排不下时，自动换行显示
   
   .cate-lv3-item {
     width: 33.33%;
     margin-bottom: 10px;
     display: flex;
     flex-direction: column;
     align-items: center;
     
     image {
       width:60px;
       height: 60px;
     }
     
     text {
       font-size: 12px
     }
   }
 }
 
</style>
